M&P9 Pro Long problems

Well-Known Member2016 Volunteer

So my uncle just purchased a (what he calls) M&P9 long slide, 5" barrel. (I have no connection to this weapon what so ever) The problem is when he inserts a mag the gun goes into battery. It doesnt happen all the time. He's been testing it with snap caps and no fingers touching the slide release. Slide still drops. A S&W armorer told him its normal and to expect it. I called BS. Hes starting to get into competition and cant have things like this happen. Ive got emails between him and S&W which ill post at the appropriate times. They told him that when the mag is inserted with enough force the slide stop will "jump" and go into battery. I call BS. I feel its a weapon malfunction. Im about %100 sure hes not slamming that mag as hard as i do when im in the heat of competition. My XDM has NEVER done that. Can someone help us?

Bronze SupporterBronze Supporter

It's normal. My wifes M&P 9L Pro will do it 100% with loaded mags. Heck---most of my Glocks,
and at least one of my 1911's will do it at least some of the time--but the M&P does it every time.
On a competion gun that's called a "feature".

Well-Known Member2016 Volunteer

Life MemberLifetime Supporter2016 Volunteer

This issue has been around for many years and is quite common with several gun manufactures. There are many variables at play as to why it happens, but the simple fact is, most pistols will do it to some degree or another. My M&P 9 CORE 5in. does it near 100% of the time and had Glocks that would do it on occasion.

There are folks that actually prefer that the gun chambers when the mag is inserted, as there is no need to hit the slide stop, hince the term "feature". I would never personally trust it to do it all the time in a defensive situation!

Bronze SupporterBronze Supporter2017 Volunteer

I have an M&P9c and an M&P40, both do it, but not every time, it seems to be linked to how hard I slam the mag in there. I asked about it a while back at a defensive handgun course and got the same response as you're getting here - it's 'normal' for some guns, and desirable by some too. Honestly, in the defensive class, it was nice to remove the step of racking the slide when doing a quick mag change during a drill.

Well-Known Member

My Glocks will do it, my XD won't...just depends on the firearm. The mag is being pressed in past the mag release and is pressing up the slide lock release lever. At work, the M&Ps will do it as well...it's not designed to do it, but it happens.

Bronze SupporterBronze Supporter

Member

my real only concern with this feature is the inconsistency of it. i want to work everytime. what if i need to do the needful and i reload and it doesn't go back into battery? and i am expecting it to go back into battery on its own. then i have to stop work the slide then get back into it.

About half of the Glock's I've owned do this, the Sig Pro would do this, and would occasionally drop the slide on even a "normal" reload. My CZ-75 full size would do this. I had a Charles Daly 1911 that did it once in a while.

What happens is that you slam the mag home and the inertia causes the slide to move and thus takes tension off your slide stop lever and Whammo - the gun goes into battery.

It's not something I would count on every time - I would still (and do) train to cycle the slide manually upon inserting a mag to avoid the training scar of counting on the slide dropping on it's own - then when/if crap goes south - you don't have that hiccup or "oh shart" moment when you reload your gun, count on the slide going home by itself, and then it doesn't and all you get is nothing when you pull the trigger again.

Not a malfunction, not really a "feature" - just something that happens. Wouldn't get worked up over it, and wouldn't ditch the platform because of it, but if it stresses him I'd gladly buy his dysfunctional longslide for $250

Well-Known Member2016 Volunteer

I really appreciate everyone's responses. I've actually learned a lot about this through this thread and speaking with other shooters. I've never had a gun do it. My XDM, BDA.45 and gen 1 G17 don't. I didn't realise it was such a common and somewhat preferred "feature". I've relayed the info given. He and his wife have both shot a match with it and also prefer the slide going into battery upon mag insertion.

In my opinion I thought that it would cause some safety issues which apparently I'm wrong about. I simply figured, which they did also, that if I didn't initiate the slide drop something must be wrong. I know mods can help this but I/we didn't think a new gun out of the box would do it. Now I'm kinda jealous.......

Well-Known Member

I really appreciate everyone's responses. I've actually learned a lot about this through this thread and speaking with other shooters. I've never had a gun do it. My XDM, BDA.45 and gen 1 G17 don't. I didn't realise it was such a common and somewhat preferred "feature". I've relayed the info given. He and his wife have both shot a match with it and also prefer the slide going into battery upon mag insertion.

In my opinion I thought that it would cause some safety issues which apparently I'm wrong about. I simply figured, which they did also, that if I didn't initiate the slide drop something must be wrong. I know mods can help this but I/we didn't think a new gun out of the box would do it. Now I'm kinda jealous.......

Active Member

I think the manual for the regular M&P is the same as the M&P Pro and on page 17 it states:

WARNING: DO NOT USE EXCESSIVE UPWARD FORCE
WHEN INSERTING A LOADED MAGAZINE INTO THE
PISTOL. EXCESSIVE UPWARD FORCE COULD CAUSE
THE SLIDE TO MOVE FORWARD, CHAMBERING A ROUND
AND MAKING THE PISTOL READY TO FIRE.

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